The object of the present invention is a method and a machine for mounting tires on wheels; the invention concerns the mounting of tires of utility vehicles, notably, trucks, farm machinery and handling equipment. It pertains, in particular, to the mounting of tires bead by bead on the rim of a wheel.
The present mounting machines (for example, as disclosed in U.S. Pat. Nos. 3,461,938 and 3,978,903) usually carry out simultaneously mounting of the two beads of the tire over the flanges of the wheel rim. In the most general case of tubeless tires, the tire is then brought to an inflation station where the two beads are simultaneously pushed on their respective seats to ensure tightness before inflation.
This method conceivably subjects the beads and the rim to considerable stresses which can damage them; that is remedied, as far as the beads are concerned, by application of a lubricating liquid on the rim seats (U.S. Pat. No. 3,658,152) before expansion of the beads.
U.S. Pat. No. 4,621,671 discloses a method and a machine for mounting tires bead by bead on a wheel with a rim having two flanges and a groove. The method of placement of the first bead consists of:
engaging a first bead around a corresponding arc of a first rim flange in order to bring that arc inside the tire; PA0 placing a roller in a given position relative to the wheel and tire assembly; and PA0 carrying out a relative displacement of the wheel and tire assembly and of the roller in order to bring the rest of the first rim flange inside the tire and thus complete placement of said first bead. PA0 the first bead is engaged around a corresponding arc of the first rim flange in order to bring that arc of the rim flange inside the tire; PA0 a mounting roller is applied against the wall of the tire opposite the first bead already engaged; PA0 the mounting roller and the wheel are displaced in relation to each other by a movement which separates the mounting roller from the arc of the first rim flange already inside the tire, that movement following a curved path relative to the plane P.sub.c of the first rim flange and the concavity of the movement being turned on the side of said wheel, so that the first rim flange is progressively engaged against the first bead until its complete entrance inside the tire. PA0 a first rotation of amplitude a of the wheel and tire assembly is made around the axis of rotation A; then PA0 a translation of the wheel and tire assembly is made until the mounting roller is applied against the wall of the tire opposite the first bead already engaged; and PA0 placement of the first bead is completed by a rotation of the tire and wheel assembly to an angle .beta.. PA0 a hub to which the wheel receiving the tire to be mounted is fitted; PA0 a mounting roller of horizontal axis R; and PA0 means of relative displacement of the hub and mounting roller, characterized in that these means make it possible to bring said hub mounting roller closer at a given distance and to carry out a rotation of the hub of horizontal axis A parallel to the axis of the mounting roller between a vertical position of the hub and a horizontal position of the hub.
In this method, the wheel is laid flat (with the wheel axis vertical), the roller is placed in front of the tire and wheel assembly on the side of the arc of the first flange already in the tire and at a given distance from the outer plane P.sub.c of the first rim flange; the relative displacement of the wheel and tire assembly and roller is then a translation such that the distance between the roller and the outer plane P.sub.c of the first rim flange remains appreciably constant and close to zero.
This machine makes it possible to reduce appreciably the stresses of mounting the first bead in the rim groove.
Another problem concerns the present wheels, which are increasingly made of an aluminum-base light alloy in order to be less heavy and offer a greater variety of shapes. These wheels are less hard than the steel rims and the feed and placement means of the usual machines are often apt to damage them, for example, when locking the flanges of the wheel rims for the mounting.